There’s something perversely fascinating about educational policies that are clearly at odds with the available data. Huge schools are still being built even though we know that students tend to fare better in smaller places that lend themselves to the creation of democratic caring communities. Many children who are failed by the academic status quo are forced to repeat a grade even though research shows that this is just about the worst course of action for them. Homework continues to be assigned – in ever greater quantities – despite the absence of evidence that it’s necessary or even helpful in most cases.

The dimensions of that last disparity weren’t clear to me until I began sifting through the research for a new book. To begin with, I discovered that decades of investigation have failed to turn up any evidence that homework is beneficial for students in elementary school. Even if you regard standardized test results as a useful measure, homework (some versus none, or more versus less) isn’t even correlated with higher scores at these ages. The only effect that does show up is more negative attitudes on the part of students who get more assignments.

In high school, some studies do find a correlation between homework and test scores (or grades), but it’s usually fairly small and it has a tendency to disappear when more sophisticated statistical controls are applied. Moreover, there’s no evidence that higher achievement is due to the homework even when an association does appear. It isn’t hard to think of other explanations for why successful students might be in classrooms where more homework is assigned – or why they might spend more time on it than their peers do.

The results of national and international exams raise further doubts. One of many examples is an analysis of 1994 and 1999 Trends in Mathematics and Science Study (TIMSS) data from 50 countries. Researchers David Baker and Gerald Letendre were scarcely able to conceal their surprise when they published their results last year: “Not only did we fail to find any positive relationships,” but “the overall correlations between national average student achievement and national averages in [amount of homework assigned] are all negative.”